Nick996

I have a 2011 GS (6spd, F55) with the OEM Z06 exhaust manifolds, cats, h-pipe and dual mode mufflers. I also installed the Z06 OEM air intake (snorkle) to get rid of the stupid air box on the side of the LS3 snorkle. I understand the intakes are the same with the exception of the square airbox on the side of the LS3 unit.

I have yet to get a tune but if I did, how close would the gains be in comparison to my car with an aftermarket air intake, headers, HFC and full exhaust? Would it be 75% of the gains? 50% of the gains? I've searched and haven't really seen anyone that did this and was able to compare results.

Also if I was to get a tune, I was thinking of adding a mild cam to make the "mods" worth while but I'm not sure if the gains would be worth the cost.

I'm on the fence with this so just looking for comments/input from everyone.

FloydSummerOf68

I'd bet you'd be 65%-75%, especially if you punched out the cats. The stock cats, even Z06 cats, are probably what would hold you back.

Totally just a guess though.

Boomer111

I can not help with the cam question, to many variables with cam choice. I can tell you though that I was 422 both rwhp and rwtq in my 08 LS3 with AR headers 1 3/4 in. w/cats and Vararam intake and 160 degree stat. Including tune.
Replaced the headers with ZO6 unit including the ZO6 H pipe into Corsa Sports. Installed stock intake and retuned. New numbers were 403 rwhp and 394 rwtq.

BUT take note that a 4:10 differential was installed after the first dyno but before the
second. Seems as if popular opinion calls for a conservative 10 hp less dyno showing when going from 3:42's to the 4:10's. So corrected numbers might look more like 415 rwhp and 405 rwtq. A loss of 7 hp and a bigger hit in the tq. Which was expected, of 17 tq.

I am stil skeptal though of the loss due to gear change. I was 400 both tq and hp with just a tune only. Seems that adding the ZO6 system should give me more that 5 lbs. Tq. 15 hp seems more pausible.

0Anthony @ LGMotorsports

Of course we have done a number of header installs.....

I have done a couple full Z06 installs on LS2 and LS3 cars as well over the years. Full manifolds, cats, mid pipes, and mufflers.

From what I have seen the manifolds with no other changes are worth 10-14 rwhp over the factory base manifolds and cats. The headers generally double that...so yes the Z06 manifolds and cats with the mid section and mufflers are worth roughly half of what a full long tube setup.

Nick996

Are these numbers before tuning? If so, what is a ballpark HP/TQ gains from what I listed in my original post above?

And then can you tell me what a ballpark estimate is for a cam + install + tune? I don't know of a cam but it would be just a cam with no valve spring changes as I am told the OEM springs are just fine for a mild cam on my GS.

Thanks!!

0Anthony @ LGMotorsports

We tuned both cars.


I don't know of any aftermarket cam that would be worth the hassle of installing that would still work with the factory LS3 valve springs.

Yawlak80-86

#1 Did you need to modify the car or the z06 exhaust to make it fit? I thought the enigne in a Z06 sat in a different place than other C6's.

#2 I didn't think there was a significant gain to be had by installing headers in a stock Z06, (less than 10 hp) as the factory exhaust flows well, (perhaps I'm mistaken). If I am correct, how would headers be more efficient in a smaller engine? If I am incorrect, please set me straight. Thanks

HOXXOH

I pretty much agree with Anthony (LG) that a full Z06 setup is about 50-60% of the expected 25 HP available from headers on the LS3 motor. I've had both and had no issues installing either.

The difference is headers provide better flow characteristics. In this case, bigger is not necessarily better.

0Anthony @ LGMotorsports

1. On manual cars everything bolts right up. All of the brackets are in the same place and the frame has enough room to fit it all. NO issues.

2. There has been a big debate about that as well but we still continue to see 25-30 hp and 30-40 ft-lbs using the headers and tunes on the Z06's. The biggest thing is torque...most LS7's will gain in the area of 40 ft-lbs at the rear tires with our 1 3/4" headers on them...no tune in the world will gain that. Not only that but the headers also drop 27 lbs of weight over the OEM system....even more if you go to aftermarket mufflers, it is very possible to drop 50 lbs from the car.

SUB VETTE

Why did you remove the headers in the first place?

Boomer111

Emissions testing in California. Did not want the hassle of guessing if I could find a place to pass the car. No biggie now I have no worries.

Bill Curlee

Very cool post!

SUB VETTE

Understand. I have the test coming up in a couple of months, that's why my AR Headers are still in the box until that's over with.

PRE-Z06

I did back to back testing of switching from 3.42 to 4.10s and it was worth 12rwhp at ~ the same power level as you were.

OP the only cams that come to mind that'd work with the stock valvesprings would be the GT2-3 or Hot Cam and even a tiny aftermarket like my 218/230 116 .605/.604 would see double the gains. Plus it'd work great with the LS7 manifolds, a total sleeper.

Boomer111

[QUOTE=PRE-Z06;1579531365]I did back to back testing of switching from 3.42 to 4.10s and it was worth 12rwhp at ~ the same power level as you were.

Thanks, this is why I came up with the 415 number with the addition of the gear change.

Boomer111

You will enjoy the AR Headers. But you will still have to deal with the testing at another date, even upon selling. 2 years goes by quickly.

0Cunningham Motorsports

i have done quite a few ls7 manifold swaps. its worth a solid 10-15 rwhp with minimal tuning required....you will need front o2 extensions

glenB

You can open the conduit and reroute the O2 harness down the back side of the head , it will reach.

0Cunningham Motorsports

yeah i know you can do that.. but i try to not modify customers harnesses if i dont have to..

Nick996

*UPDATE*

I wanted to update this thread so if someone is doing research, all the info is in one place.

Finally had the car tuned.

http://forums.corvetteforum.com/c6-s...e-results.html